Reference of method Static - small program example to advice

I am stuck with this program below regarding one thing and it is... How can value "17" get to method isPrime when in method numTest it is separated by comma and I can´t find any transfer of this value "17" to this method? Thank you much for helping me move further. Can anybody explain me pls movement of value "17"?

// Demonstrate a method reference for a static method. 

// A functional interface for numeric predicates that operate 
// on integer values. 
interface IntPredicate { 
  boolean test(int n); 
} 

// This class defines three static methods that check an integer 
// against some condition. 
class MyIntPredicates { 
  // A static method that returns true if a number is prime. 
  static boolean isPrime(int n) { 

    if(n < 2) return false; 

    for(int i=2; i <= n/i; i++) { 
      if((n % i) == 0)  
        return false; 
    } 
    return true; 
  } 

  // A static method that returns true if a number is even. 
  static boolean isEven(int n) { 
    return (n % 2) == 0; 
  } 

  // A static method that returns true if a number is positive. 
  static boolean isPositive(int n) { 
    return n > 0; 
  } 
}     

class MethodRefDemo { 

  // This method has a functional interface as the type of its 
  // first parameter. Thus, it can be passed a reference to any 
  // instance of that interface, including one created by a 
  // method reference. 
  static boolean numTest(IntPredicate p, int v) { 
    return p.test(v); 
  } 

  public static void main(String args[]) 
  { 
    boolean result; 

    // Here, a method reference to isPrime is passed to numTest(). 
    result = numTest(MyIntPredicates::isPrime, 17); 
    if(result) System.out.println("17 is prime."); 

    // Next, a method reference to isEven is used. 
    result = numTest(MyIntPredicates::isEven, 12); 
    if(result) System.out.println("12 is even.");  

    // Now, a method reference to isPositive is passed. 
    result = numTest(MyIntPredicates::isPositive, 11); 
    if(result) System.out.println("11 is positive."); 
  } 
}